二维码与短链接整合实战：从生成到扫描的数据追踪链路

package main

import (
    "image/png"
    "os"
    
    "github.com/skip2/go-qrcode"
)

func GenerateQRCode(shortURL string, outputPath string) error {
    // ErrorCorrectionMedium 容错 15%，适合打印场景
    qr, err := qrcode.New(shortURL, qrcode.Medium)
    if err != nil {
        return err
    }
    
    // 设置尺寸和颜色
    qr.BackgroundColor = qrcode.White
    qr.ForegroundColor = qrcode.Black
    
    file, _ := os.Create(outputPath)
    defer file.Close()
    
    return png.Encode(file, qr.Image(256))
}

func GenerateBrandedQR(shortURL string, logoPath string, outputPath string) error {
    qr, _ := qrcode.New(shortURL, qrcode.High) // High 容错率支持中间遮罩
    
    // 256x256 画布
    img := qr.Image(256)
    
    // 叠加 Logo（尺寸不超过 20%）
    logo := loadImage(logoPath)
    overlayLogo(img, logo, 0.15)
    
    return savePNG(outputPath, img)
}

func QRRedirectHandler(w http.ResponseWriter, r *http.Request) {
    shortCode := extractShortCode(r.URL.Path)
    
    // 1. 解析 User-Agent
    ua := useragent.Parse(r.UserAgent())
    
    // 2. 解析 IP 归属
    location := geoip.Lookup(r.RemoteAddr)
    
    // 3. 记录扫描事件
    event := ScanEvent{
        ShortCode:  shortCode,
        Timestamp:  time.Now(),
        OS:         ua.OS,
        Device:     ua.Device,
        City:       location.City,
        SourceApp:  detectSourceApp(r.Header.Get("Referer")),
        LatencyMs:  0,
    }
    
    // 4. 异步上报（不阻塞跳转）
    analytics.TrackAsync(event)
    
    // 5. 执行跳转逻辑
    targetURL := resolveTarget(shortCode, event)
    http.Redirect(w, r, targetURL, http.StatusFound)
}

func resolveTarget(shortCode string, event ScanEvent) string {
    qrRule := db.GetQRRule(shortCode)
    
    switch {
    // 微信内 → 公众号文章 / 小程序
    case event.SourceApp == "wechat":
        if qrRule.WechatURL != "" {
            return qrRule.WechatURL
        }
        return qrRule.FallbackURL
    
    // iOS → Universal Link / App Store
    case event.OS == "iOS":
        if isAppInstalled(event) { // 通过 Universal Link 判断
            return qrRule.UniversalLink
        }
        return qrRule.AppStoreURL
    
    // Android → App Links / 应用宝
    case event.OS == "Android":
        if event.SourceApp == "wechat" {
            return qrRule.YybURL // 应用宝微下载，微信内可跳转
        }
        return qrRule.AppLink
    
    // 默认 fallback
    default:
        return qrRule.FallbackURL
    }
}

func GenerateOneProductOneCode(productSKU string, batchID string) string {
    // short.link/p/{sku}-{batch}-{seq}
    shortCode := fmt.Sprintf("p-%s-%s-%d", productSKU, batchID, nextSeq())
    
    // 查询是否首次扫码
    isFirstScan := !redis.Exists("scan:" + shortCode)
    
    if isFirstScan {
        return "https://brand.com/first-reward?code=" + shortCode
    }
    return "https://brand.com/product-info?sku=" + productSKU
}

func BatchGenerateQRCodes(ctx context.Context, req BatchQRRequest) (*BatchQRResponse, error) {
    codes := make([]QRPair, 0, req.Count)
    
    for i := 0; i < req.Count; i++ {
        // 1. 生成短链
        shortCode := generateShortCode()
        
        // 2. 保存规则
        db.SaveQRRule(QRRule{
            ShortCode:    shortCode,
            DefaultURL:   req.DefaultURL,
            WechatURL:    req.WechatURL,
            IOSURL:       req.IOSURL,
            AndroidURL:   req.AndroidURL,
            ExpireAt:     req.ExpireAt,
        })
        
        // 3. 生成二维码图片
        shortURL := "https://short.link/" + shortCode
        imgPath := generateQRImage(shortURL, req.Style)
        
        codes = append(codes, QRPair{
            ShortCode: shortCode,
            QRImage:   imgPath,
        })
    }
    
    return &BatchQRResponse{Codes: codes}, nil
}